The present invention relates generally to flow control devices and more particularly to a rotary pipe switch which operates to selectively interconnect a central pipe with one of a plurality of distributing pipes arranged in a circular pattern around the central pipe.
Examples of prior art devices of the type to which the present invention relates may be found in German Auslegeschrift No. 18 14 588 which discloses a rotary pipe switch for pneumatic conveying plants. A switch of this type is formed with an S-shaped rotary pipe which is rotatably supported with its upper end in a main pipe and which has a lower end which can be connected to a plurality of branch pipes arranged in a circular pattern. The rotary pipe is constructed in two pieces and it has a hydraulic working cylinder which is joined with one end to the upper portion of the rotary pipe and with its other end to the lower portion of the rotary pipe. By means of the working cylinder, the lower portion of the rotary pipe can be pressed tightly onto the distributing pipe or it may be lifted therefrom.
Such known rotary pipe switches are suitable for pneumatic conveying plants utilizing dust-like or granular materials. The pipelines used in this type of application will have a relatively small inside cross sectional dimension and will be capable of easy manipulation.
Another type of prior art device known from German Auslegeschrift No. 18 12 367, involves a pipe switch wherein an incoming pipe may be selectively connected to a plurality of outgoing pipes through a flexible pipe and a rigid pipe. The rigid pipe is arranged at the end of the flexible pipe and arranged at the rigid pipe section is a thrust piston for swinging the flexible pipe. In the region of the rigid pipe section there are provided lifting elements which operate to effect slight movement in the axial direction of a connecting piece arranged at the lower end of the rigid pipe section.
Accordingly, the connecting piece can be lifted from an outgoing pipe, the thrust piston drive for effecting swinging movement can be subsequently actuated and the connecting piece can be finally brought into firm contact with another outgoing pipe by means of the lifting cylinders.
In technological areas of activity relating to partial vacuums and excess pressures, it is frequently necessary to connect a particular one of a plurality of user systems to a central generator for a partial vacuum or an excess pressure, while other user systems are not required. Generator and user systems of this type are provided with a stationary pipe system which is equipped with valves. However, unlike pipe switches, valves tend to be very sensitive when exposed to dirt or contamination. Thus, in the case of valve control devices utilizing several valves, failure of only one contaminated valve may cause malfunction of an entire control system.
In applications where large pipe dimensions are involved, pipe systems with several individual lines may be arranged in a relatively complicated pattern thereby requiring a substantial amount of space. Such systems are found, for example, in vacuum lines for the degasification of steel, in large gas lines utilized in the steel industry or in large ventilating and air removal systems where diameters of 1,000 mm or more may be involved. Moreover, cumbersome control and regulating mechanisms will be required for switching individual lines into a central line.
The present invention is directed toward providing a rotary pipe switch, particularly applicable where pipes with large dimensions may be involved, which is easy to operate, relatively simple in its design, does not require excessive space and avoids arrangements of pipe lines in complicated patterns.